1. Field of the Invention
The invention relates to a method of determining the nuclear magnetisation distribution in a limited volume by means of a plurality of sequences, three r.f. pulses being applied to an examination zone in each sequence in the presence of a steady, uniform magnetic field, the first and the second r.f. pulse cooperating with a respective one of two magnetic fields whose gradients extend perpendicularly with respect to one another, the stimulated echo signals generated in each sequence being added and subjected to a Fourier transformation, and also relates to a device for performing the method.
2. Description of the Prior Art
A method of this kind is known from EP-OS No. 87 200 261 which was published under EPO No. 233675, and to which commonly owned U.S. Pat. No. 4,843,549, issued June 27, 1989, corresponds. A drawback of this method consists in that also the third one of the three r.f. pulses is a so-called layer-selective pulse which is generated in conjunction with a magnetic gradient field and in that a magnetic gradient field is switched on and off again after this pulse and briefly before the reception of the stimulated echo signal. The magnetic gradient field during and after the r.f. pulse generate eddy currents which are active for a longer period of time than the magnetic gradient fields generating these eddy currents. The eddy currents in their turn cause magnetic fields which have a disturbing effect on the phase of the stimulated echo signal.